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Thallium and co-genetic trace elements in hydrothermal Fe-Mn deposits of Central Spain
Thallium (Tl) is a hazardous trace metal that can harm human and environmental health. Tl pollution can result from the mining and smelting of Tl-bearing minerals, but also the natural weathering of Tl-bearing sulfide minerals may induce Tl release to the environment. In this study, hydrothermal dep...
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Published in: | The Science of the total environment 2020-05, Vol.717, p.137162-137162, Article 137162 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
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Online Access: | Get full text |
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Summary: | Thallium (Tl) is a hazardous trace metal that can harm human and environmental health. Tl pollution can result from the mining and smelting of Tl-bearing minerals, but also the natural weathering of Tl-bearing sulfide minerals may induce Tl release to the environment. In this study, hydrothermal deposits hosted in dolostone rocks sited along fossil thermal springs in the Lodares region (Soria province, central Spain) were studied. In this hydrothermal mineralization zone, Tl association with primary minerals, identified Tl-bearing secondary products resulting from natural weathering of primary minerals, as well as the dispersion from its natural source along a seasonal small streambed were explored. Samples were analyzed by chemical, microscopic and spectroscopic techniques and epithermal pyrite, sphalerite, galena and barite and secondary gypsum, jarosite, scorodite, anglesite, goethite, epsomite and elemental sulfur produced by both inorganic and bacterial processes were found. The highest Tl contents were found in hydrothermal pyrite (188 mg kg−1), jarosite (142 mg kg−1), Mn-oxides (27 mg kg−1) or kerogen (13 mg kg−1). Feldspar was identified by electron probe microanalysis as potential host phase of Tl. XANES results confirmed the association of Tl(I) with metal sulfides in pyrite-rich samples and highlighted the role of jarosite-like minerals for Tl(I) sequestration upon pyrite oxidation, even in carbonate-rich samples at near-neutral pH. In addition to micaceous minerals, jarosite-group minerals and K-feldspars may contribute to the natural attenuation of Tl in soils and sediments.
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•We study Tl mineralogy in epithermal deposits within dolostones in Central Spain.•The highest Tl contents were found in hydrothermal pyrite.•XANES confirms the association of Tl with metal sulfides in pyrite-rich samples.•XANES shows Tl-jarosite as main secondary phase after pyrite oxidation.•Tl in pyrite-rich and sediment samples is present as Tl+. |
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ISSN: | 0048-9697 1879-1026 |
DOI: | 10.1016/j.scitotenv.2020.137162 |